1. Field of the Invention
The present invention relates to an image recording apparatus and a control method thereof. More specifically, the present invention relates to the image recording apparatus wherein a recording head and a recording material are relatively moved to perform recording and the control method thereof. Still more specifically, the present invention relates to the control method that a roll paper and a cut paper are inserted through a common paper feed port and conveyed.
2. Description of the Related Art
Generally, an ink jet recording apparatus performs recording such that an ink is discharged from a recording head onto a recording material. Downsizing of the recording head can be achieved with ease, a high-resolution image can be recorded at high speed, an inexpensive running cost can be achieved, and a noise can be reduced because of a non-impact system. Further, the ink jet recording apparatus has an advantage that a color image can be recorded with ease by using multiple color inks.
Generally, the inkjet recording apparatus can record an image onto various types of recording materials such as a sheet. More specifically, the ink jet recording apparatus can use various types of sheets such as a calendered paper and a coated paper, various sizes of sheets such as A4 typical size and A0 typical size, and a plurality of types of sheets such as a cut paper and a roll paper. By using the above features, a print product to be used in various fields such as a point-of-purchase advertisement (POP) and a poster can be produced in addition to general printed matters such as a document and a photograph.
FIG. 7 of Japanese Patent Laid-open Publication No. 08-324052 discusses a known image recording apparatus having a configuration that a cut paper and a roll paper wound around a spool can be inserted through a common paper feed port. In the image recording apparatus having the above descried configuration, prior to a supply of the sheet to the image recording apparatus, information as to which sheet of the roll paper or the cut paper is to be conveyed is input via some sort of selecting unit into the image recording apparatus. As described above, a type of sheet is preliminarily notified to the image recording apparatus, so that an optimum control can be performed according to the types of sheets with respect to various operations including paper feeding, image recording (e.g., printing), and paper discharging. Japanese Patent Laid-open Publication No. 2002-234222 discusses an image recording apparatus having a configuration that any one of a plurality of buttons provided on an operation panel of the image recording apparatus is pressed in order to select the type of sheet. Japanese Patent Laid-open Publication No. 2001-97582 discusses an image recording apparatus having a configuration in which the selection of the type of sheet is carried out according to a length of time for pressing a single button.
An image recording apparatus having a configuration that the roll paper and the cut paper are discharged from a common conveyance path is also known. The desirable image recording apparatus having the above configuration specifies the type of sheet to be discharged, by the above described means for selecting the type of sheet and performs the optimum control in discharging the sheet. Japanese Patent Laid-open Publication No. 2001-97582 discusses an image recording apparatus that discriminates the type of sheet according to whether a trailing edge of the sheet is detected at a predetermined position within a predetermined conveyance amount when the sheet is conveyed to a downstream portion for the sake of discharging the sheet after recorded.
Japanese Utility Model Application Laid-open Publication No. 07-31391 discusses an image recording apparatus that determines the type of sheet, i.e., whether the sheet inserted into the paper feed port (i.e., an entrance section of the conveyance path of the sheet) is the roll paper or the cut paper when it is conveyed to a section for forming an image (i.e., an image forming unit) within the apparatus. In the image recording apparatus discussed in Japanese Utility Model Application Laid-open Publication No. 07-31391, presence or absence of a rotation of a spool holding the roll paper enables a determination of the type of sheet and a result of the determination is used in deciding whether it is necessary or unnecessary to cut the sheet after an image recording operation.
As described above, the image recording apparatus controls a conveyance of sheet according to the type of sheet selected by a user. Therefore, in a case where the selected type of sheet matches the type of sheet actually fed and conveyed, a normal and optimum conveyance of the sheet is performed. However, in a case where the type of sheet disagrees with the type of sheet actually fed and conveyed, many problems occur.
For example, the following problem may occur at a time of feeding a sheet (at a time of conveyance of a sheet after a start of conveyance of the sheet and immediately before the recording of the sheet). A case is considered where a cut paper is inserted into a paper feed port when the roll paper is selected as the type of sheet (hereinafter referred to as the “roll paper mode”). In this case, when the cut paper is fed, the cut paper is pinched by a line feed roller (hereinafter referred to as the “LF roller”) pair, made of a line feed roller and a pinch roller, which are placed at an upstream side of the image forming unit, and largely conveyed in a downstream direction. Since the sheet has an enough length in a case of the roll paper, a skew correction and a skew detection of the roll paper can be performed by the above processing. However, since the cut paper has less sheet length, the sheet may be discharged to an outside of the apparatus or an error indicating a run-out of paper is erroneously detected, causing a suspension of an operation of the apparatus. Further, a case is considered where the roll paper is inserted into the paper feed port when the cut paper is selected as the type of sheet (hereinafter referred to as the “cut paper mode”). In this case, a leading edge of the roll paper is brought into contact with the LF roller pair to form a predetermined loop in the upstream side of the roller pair. Then, the roll paper is pinched by the LF roller pair to be conveyed to the downstream image forming unit. In a case of the cut paper, since the leading edge of the sheet is straightly aligned, a skew correction and a positioning can be performed in the above described manner. However, since the leading edge of the roll paper is not sometimes straightly aligned, if the roller paper is fed in the same manner as it is done for the cut paper, the roller paper may be skewed for this sake or a paper jam may occur.
At the time of discharging the sheet (i.e., when the sheet is conveyed to be discharged outside the apparatus after an image is recorded thereon), the following problem may occur. In the roll paper mode, the sheet is cut by a cutter at an upstream portion of the sheet where the image is formed, thereby cutting out the sheet from a rolling portion of the roll paper. In a case of the roll paper, no problem occurs since the sheet has the enough length. However, in a case where the sheet is the cut paper, since the sheet has a shorter length, an error indicating a run-out of the cut paper is detected while the cut paper is conveyed, thereby suspending a conveyance operation. If the roll paper is discharged when the apparatus is in the cut paper mode, the apparatus tries to convey the sheet to the downstream side (i.e., in a paper discharge direction) until a trailing edge of the sheet is detected. In a case where the sheet is the cut paper, since the sheet has a shorter length, the trailing edge of the sheet is immediately detected and the conveyance of the sheet is suspended, resulting in normal discharge of the sheet. However, since the roll paper has longer sheet length, the trailing edge of the sheet is not detected however much the sheet is conveyed and thus a large amount of roll paper is wound off. When the trailing edge of the sheet is not detected before a predetermined conveyance amount is conveyed, a countermeasure, e.g., suspension of the conveyance of the sheet, may be taken. However, if a normal discharge of the cut paper of a larger size such as A0 typical size (i.e., 841×1189 mm) is considered, the predetermined conveyance amount cannot be set to a small value and thus the roll paper may be wound off uneconomically.